— How does Jack usually go to school?

— He _____ ride a bike, but now he ______ there to lose weight.

A．used to; is used to walk

B．was used to; is used to walking

C．was used to; is used to walk

D．used to; is used to walking

不是影响胃排空速度的因素是

A．空腹与饱腹

B．药物因素

C．食物的组成

D．药物的多晶型

E．食物的性质